The present invention relates to a filter system comprising a cup-shaped housing releasably connected to a connecting head or receiving head and a filter element arranged in the housing. The invention additionally relates to a connecting head for a filter system of the aforementioned type, to a cup-shaped housing for a filter system of the aforementioned type, to a filter element for a filter system of the aforementioned type, and to a method of servicing a filter system of the aforementioned type.
A liquid filter of this type is known, for example, from U.S. Pat. No. 5,888,384 (=DE 196 44 647). This filter has a connecting head whose installation opening for the filter cartridge points downward and into which a cup-shaped housing can be screwed after installing the filter element. The inlet and outlet for the filter and/or the filter system are located in the connecting head, i.e., in the upper part of the filter system.
A potential problem with this filter system is that the connecting head and the cup-shaped housing can be joined together without inserting a filter element, or even if the wrong filter element, i.e., one not intended for this system, is inserted. As a countermeasure to prevent such errors, prior art filter elements have been constructed with different shapes so that the possibility of a mix-up can be ruled out as much as possible. However, such measures will not necessarily prevent the absence of a filter element from going unnoticed.
Furthermore, there are other applications in which the filter elements differ with regard to details such as different filter media, but the dimensions and geometries remain substantially identical. Here again, there is a potential problem of installing the wrong filter element in the filter system, which can result in major damage in the fluid circuit.